<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      /*
       *封装一个 sendAjax 发送 GET AJAX 请求
       *参数 URL
       *返回结果 Promise 对象
       */
      function sendAJAX(url) {
        return new Promise((reslove, reject) => {
          const xhr = new XMLHttpRequest();
          xhr.open('GET', url);
          xhr.send();
          xhr.onreadystatechange = function () {
            if (xhr.readyState === 4) {
              if (xhr.status >= 200 && xhr.status < 300) {
                reslove(xhr.response);
              } else {
                reject(xhr.status);
              }
            }
          };
        });
      }
      sendAJAX('http://poetry.apiopen.top/sentences').then(
        (value) => {
          console.log(value);
        },
        (reason) => {
          console.warn(reason);
        }
      );
    </script>
  </body>
</html>
